Gas collector for epitaxial reactors

ABSTRACT

A gas collector is disclosed for use with epitaxial reactors. The gas collector is in the form of a base and top portion that are interconnected by means of a sealing arrangement. The top portion is configured to cover the base and define a conduit therebetween. Inlets and outlets are provided to direct chemical vapors from a reaction chamber of the epitaxial reactor into the conduit and further into an exhaust pipe of the epitaxial reactor. The gas collector is capable of forming a hermetic seal with the lid of the reaction chamber in order to prevent escape of chemical vapors.

This application is a Continuation of application Ser. No. 09/635,268filed Aug. 9, 2000, now U.S. Pat. No. 6,325,855 B1.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to epitaxial reactors and, moreparticularly, to a gas collector for epitaxial reactors.

2. Description of the Related Art

Continuing advances in the microchip industry have resulted thedevelopment of highly complex thin-film deposition processes forfabricating semiconductor devices that are packaged for use in themanufacture of sophisticated electronic devices. Thin films of materialthat are deposited on semiconductor wafers are often referred to asepitaxial layers. High speed electronic transistors, quantum-well diodelasers, light-emitting diodes, photodetectors, and optical modulatorsincorporate structures composed of numerous epitaxial layers ranging inthickness from several microns to as thin as a few tenths of ananometer. These epitaxial layers are typically deposited, or grown, ona single-crystal substrate, i.e., the semiconductor wafer.

One method of forming epitaxial layers on a semiconductor wafer is knownas chemical vapor deposition (CVD). In a typical manufacturing processof a wafer, for example, silicon in extremely pure crystalline form isoverlayed sequentially with numerous layers of materials which functionas conductors, semiconductors, or insulators. Each subsequent layer isordered and patterned such that the sequence of layers forms a complexarray of electronic circuitry. The semiconductor wafer is subsequentlycut along predetermined scribe lines into individual devices, commonlyreferred to as “chips.” These chips ultimately function as keycomponents in electronic devices ranging from simple toys to complexsupercomputers.

CVD processes normally take place within a device such as, for example,a radial flow reactor, that includes a reaction chamber. Thesemiconductor wafer is initially placed within a reaction chamber, whichtypically contains an inert atmosphere. The temperature within thereaction chamber is elevated and chemical vapors containing the compoundor element to be deposited are introduced to react with the surface ofthe semiconductor wafer. This process results in deposition of therequired film. The chemical vapors are continually introduced andremoved from the reaction chamber until a requisite film thickness hasbeen achieved.

Reaction chambers are typically constructed from a perforated section ofsheet metal that is cut and folded into a segmented conduit of polygonalconfiguration. The segments are closely aligned so as to form asemi-continuous loop. The reactor chamber lid is pressed against the topof the conduit formed by the sheet metal in order to provide a sealbetween the conduit and the reactor chamber lid. Inlets and outlets areprovided for the chemical vapors along inner and outer circumference ofthe conduit, respectively.

One problem associated with such reaction chambers is that thesemi-continuous nature of the conduit does not always form a gas, orhermetic, seal the reactor chamber lid. Accordingly, chemical vapors areallowed to escape from the conduit to other parts of the reactionchamber prior to being channeled to the exhaust pipes. Another problemwith such reaction chambers is the potential for contamination resultingfrom repeated flexing of the sheet metal over repeated openings of thereactor chamber lid. More particularly, each time the reactor chamber isopened, the conduit flexes along the same perforations and bendingpoints. Over time, metal particulates will flake off the sheet metal andcontaminate the inert atmosphere of the reaction chamber.

There exists a need for a gas collector capable of preventing the escapeof chemical vapors removed from an epitaxial reactor. There also existsa need for a gas collector that minimizes the level of contaminationinto the epitaxial reactor.

SUMMARY OF THE INVENTION

These and other needs are addressed by the present invention, wherein agas collector is constructed from solid components that are capable offorming a hermetic seal with the lid of an epitaxial reactor.

In accordance with the present invention, a gas collector for anepitaxial reactor comprises a base, a top portion, and a sealingarrangement. The sealing arrangement is operatively coupled to the baseand top portion. The base has a U-shaped cross-section and a generallycircular configuration. The top portion is configured to cover the basesuch that a conduit is defined between the base and the top portion. Aplurality of inlets are provided to direct chemical vapors from thereactor into the conduit. Additionally, at least one outlet is providedfor directing the chemical vapors from the conduit to an exhaust pipe ofthe epitaxial reactor. According to such an arrangement, the top portionof the gas collector is capable of forming a hermetic seal with the lidof the epitaxial reactor's reaction chamber. Furthermore, the potentialfor contamination is reduced because the components of the gas collectorare formed from solid pieces of material that do not flex or bend.

Additional advantages and novel features of the present invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing, or may be learned by practice of the present invention. Theembodiments shown and described provide an illustration of the best modecontemplated for carrying out the present invention. The invention iscapable of modifications in various obvious respects, all withoutdeparting from the spirit and scope thereof. Accordingly, the drawingsand description are to be regarded as illustrative in nature, and not asrestrictive. The advantages of the present invention may be realized andattained by means of the instrumentalities and combinations particularlypointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the attached drawings, wherein elements having thesame reference numeral designations represent like elements throughoutand wherein:

FIG. 1 is an exploded view of a gas collector constructed in accordancewith the present invention;

FIG. 2 is a perspective cross-sectional view of the gas collector; and

FIG. 3 is a perspective cross-sectional view of the gas collector with aspring positioned within the conduit.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, and initially to FIG. 1, there is showna gas collector 100 for an epitaxial reactor (not shown) constructed inaccordance with the present invention. The gas collector 100 included abase 110 and a top portion 112. A sealing arrangement 114 isadditionally provided to facilitate the formation of a gas seal (i.e.,hermetic seal) between the top portion 112 and a lid of the epitaxialreactor. As can be appreciated, the gas collector 100 of the presentinvention primarily functions to collect chemical vapors (i.e., reactivegases from chemical vapor deposition) from a reaction chamber of theepitaxial reactor, and direct the chemical vapors to the epitaxialreactor's exhaust pipes.

As illustrated in FIG. 1, the base 110 of the gas collector 100 has agenerally circular configuration when examined fro m a top plan view.The base 110 includes an inner wall 116 and an outer wall 118, both ofwhich extend from a bottom portion thereof. The particular arrangementof the inner and outer walls 116, 118 results in a U-shapedcross-section for the base 110. Accordingly, a conduit 120 is definedbetween the top portion 112 and the interior of the base 110.

According to the disclosed embodiment of the present invention, the gascollector includes a plurality of inlets 122 that allow chemical vaporsto enter the conduit 120. The inlets 122 are in the form of aperturesand are diposed along the inner wall 116 of the base 110. At least oneoutlet 124 is provided to direct the chemical vapors from the conduit120 to the exhaust pipe of the reactor. As illustrated in FIG. 1, theoutlet 124 is formed on the outer wall 118 of the base 110. Depending onthe specific application and/or size of the conduit, multiple outlets124 can be provided to direct chemical vapors from the conduit 120. Insuch cases, the outlets 124 are preferably provided in pairs, andpositioned such that pairs of outlets 124 are diametrically opposite ofeach other (i.e., 180° apart). In other words, each outlet 124 is inalignment with a corresponding outlet 124 according to an alignment line(not shown) passing through the center of the gas collector 100.

According to one embodiment of the invention, at least one secondaryinlet 126 can be formed on the outer wall 118 of the base 110. Thesecondary inlet 126 facilitates introduction of purge gas into theconduit. The purge gas ensures that there is no substantial pressuredifference between the inner and outer areas of the reactor chamber.More particularly, the secondary inlet 126 provide a pathway forintroducing purge gas from the outer portions of the reactor chamberinto the conduit 120 and out to the exhaust pipes. As can beappreciated, the number of secondary inlets 126 provided will depend onthe particular epitaxial reactor and the amount of chemical vapor thatis present. A control system can be optionally provided to meter thevolume of purge gas being introduced into the conduit 120 in order toprevent chemical vapors within the conduit from entering the outer areaof the reactor chamber via the secondary inlet 126.

With continued reference to FIG. 1, and additional reference to FIGS. 2and 3, the sealing arrangement 114 will now be described. The sealingarrangement 114 is formed as part of the base 110 and top portion 112 ofthe gas collector in order to minimize the number of moving parts. Forexample, the disclosed embodiment of the present invention shows a pairof concentric grooves 130 that are formed on the bottom surface of thetop portion 112. In addition, a mating projection 132 extends from theend of the inner wall 116 and the end of the outer wall 118. The matingprojections 132 are specifically designed for insertion and engagementwith the concentric grooves 130 of the top portion 112. Depending on thespecific application, the mating projections 130 can be constructed topossess a predetermined level of resiliency to better engage theconcentric grooves 130.

The gas collector 100 of the present invention is designed to form ahermetic seal with the lid of the reaction chamber in order to preventchemical vapors from entering other parts of the reactor by means ofpassages formed between the lid of the reaction chamber and the topportion 112. According to one embodiment of the present invention, aplurality of resilient members can be disposed within the conduit toexert pressure against the top portion 112 when the lid of the reactionchamber is closed. Preferably, the resilient members are in the form ofhelical springs 134, as shown in FIGS. 1 and 3. Alternatively, anyresilient member capable of withstanding the operating conditions of thegas collector and capable of exerting the proper amount of force on thetop portion 112 can be used. The springs 134 are designed to exert anamount of force sufficient to form a hermetic seal between the topportion 112 and the lid of the reaction chamber.

As illustrated in FIG. 1, the springs 134 are arranged such that theforce against the top portion 112 is evenly distributed. Additionally,the base 110 can include a plurality of seats 136 corresponding to thenumber of springs 134. Each seat 136 is in the form of a recess, orcounter-sunk hole, within the bottom surface of the base 110. Each seat136 is configured to receive a spring 134 therein and prevent lateralmovement of the spring 134. The springs 134 have a diameter that isnearly equal to the size of the conduit 120. However, the spacing formedby the coils of the springs 134 allow chemical vapors to pass throughthe conduit 120 with very little resistance.

According to an alternative embodiment of the present invention, themating projections 130 can be constructed to possess a predeterminedlevel of resiliency in order properly form a hermetic seal between thetop portion 112 and the lid of the reaction chamber. Furthermore, thedegree of resiliency can depend on the particular epitaxial reactor andthe amount of pressure applied by the lid of the reaction chamber.

As illustrated in FIGS. 2 and 3, a ledge portion 128 protrudes from theinner wall 116 of the base 110. The ledge portion 128 has a circularconfiguration that conforms to the shape of the base 110. The ledgeportion 128 functions to support the gas collector 100 on the epitaxialreactor.

The gas collector 100 of the present invention can be constructed fromvarious types of materials capable of withstanding the operatingconditions within the reaction chamber of the epitaxial reactor. Thebase 110, top portion 112, and springs 134 can be constructed from anyof a plurality of high temperature metals and alloys, such as Iconel.For example, the gas collector 100 can be constructed from stainlesssteel, Molybdenum, graphite, etc.

In the previous descriptions, numerous specific details are set forth,such as specific materials, structures, processes, etc., in order toprovide a thorough understanding of the present invention. However, asone having ordinary skill in the art would recognize, the presentinvention can be practiced without resorting to the details specificallyset forth. In other instances, well known processing structures have notbeen described in detail in order not to unnecessarily obscure thepresent invention.

Only the preferred embodiment of the invention and an example of itsversatility are shown and described in the present disclosure. It is tobe understood that the invention is capable of use in various othercombinations and environments and is capable of changes or modificationswithin the scope of the inventive concept as expressed herein.

What is claimed is:
 1. An epitaxial reactor, comprising: a lid; achamber; and a gas collector for transferring gas from said chamber,said gas collector having a top portion, a base and resilient members,wherein said top portion is movably connected to said base, and saidresilient members exert pressure against the top portion to form a sealbetween said top portion and said lid.
 2. The epitaxial reactoraccording to claim 1, wherein said top portion and said base define aconduit between said top portion and said base.
 3. The epitaxial reactoraccording to claim 2, wherein said resilient members are disposed withinsaid conduit.
 4. The epitaxial reactor according to claim 3, whereinsaid resilient members are springs.
 5. The epitaxial reactor accordingto claim 4, wherein each of said springs are connected to a seat in saidbase.
 6. The epitaxial reactor according to claim 4, wherein saidsprings have a diameter substantially equal to a width of said conduit.7. The epitaxial reactor according to claim 3, wherein said resilientmembers are disposed within said conduit to evenly distribute saidpressure against said top portion.
 8. The epitaxial reactor according toclaim 3, wherein said resilient members permit a gas flow through saidconduit.
 9. The epitaxial reactor according to claim 1, wherein one ofsaid top portion and said base defines a groove and an other of said topportion and said base includes a projection, said projection engagingsaid groove.
 10. The epitaxial reactor according to claim 9, whereinsaid engagement of said projection with said grooves provides a movableconnection between said top portion and said base.
 11. The epitaxialreactor according to claim 1, wherein said gas collector is formed fromgraphite.
 12. The epitaxial reactor according to claim 1, wherein saidgas collector includes inlets fluidly connecting said conduit with saidchamber.
 13. The epitaxial reactor according to claim 1, wherein saidgas collector includes at least one outlet fluidly connecting saidconduit with an exhaust pipe of said reactor.
 14. An epitaxial reactor,comprising: a lid; a chamber; and a gas collector formed from graphitefor transferring gas from said chamber, said gas chamber including abase, a top portion, said top portion and said base defining a conduitbetween said top portion and said base, and one of said top portion andsaid base defining a groove and an other of said top portion and saidbase includes a projection, said projection engaging said groove to forma seal between said top portion and said base, resilient membersdisposed within said conduit, said resilient members permitting a gasflow through said conduit, and said resilient members exerting pressureagainst the top portion to form a seal between said top portion and saidlid, inlets fluidly connecting said conduit with said chamber, at leastone outlet fluidly connecting said conduit with an exhaust pipe of saidreactor.
 15. A gas collector for an epitaxial reactor having a lid and achamber, comprising: a base; a top portion movably connected to saidbase; resilient members for exerting pressure against said top portionto form a seal between said top portion and the lid.
 16. The gascollector according to claim 15, wherein said top portion and said basedefine a conduit between said top portion and said base.
 17. The gascollector according to claim 16, wherein said resilient members aredisposed within said conduit.
 18. The gas collector according to claim17, wherein said resilient members are springs.
 19. The gas collectoraccording to claim 18, wherein each of said springs are connected to aseat in said base.
 20. The gas collector according to claim 18, whereinsaid springs have a diameter substantially equal to a width of saidconduit.
 21. The gas collector according to claim 17, wherein saidresilient members are disposed within said conduit to evenly distributesaid pressure against said top portion.
 22. The gas collector accordingto claim 17, wherein said resilient members permit a gas flow throughsaid conduit.
 23. The gas collector according to claim 15, wherein oneof said top portion and said base defines a groove and an other of saidtop portion and said base includes a projection, said projectionengaging said groove.
 24. The gas collector according to claim 23,wherein said engagement of said projection with said grooves provides amovable connection between,said top portion and said base.
 25. The gascollector according to claim 15, wherein said gas collector is formedfrom graphite.
 26. The gas collector according to claim 15, wherein saidgas collector includes inlets fluidly connecting said conduit with thechamber.
 27. The gas collector according to claim 15, wherein said gascollector includes at least one outlet fluidly connecting said conduitwith an exhaust pipe of the reactor.
 28. A gas collector fortransferring gas from a chamber of an epitaxial reactor, said gaschamber comprising: a base; a top portion, said top portion and saidbase defining a conduit between said top portion and said base, and oneof said top portion and said base defining a groove and an other of saidtop portion and said base includes a projection, said projectionengaging said groove to form a seal between said top portion and saidbase; resilient members disposed within said conduit, said resilientmembers permitting a gas flow through said conduit, and said resilientmembers exerting pressure against the top portion to form a seal betweensaid top portion and a lid of the epitaxial reactor; inlets fluidlyconnecting said conduit with the chamber; and at least one outletfluidly connecting said conduit with an exhaust pipe of the reactor,wherein the gas collector is formed from graphite.